The present invention relates generally to a hermetic compressor and more particularly to small refrigeration compressors used in household appliances. An area of interest in the compressor art is how to construct a quieter compressor. In the past, excessive sound and vibration has emanated from the compressor housing.
Prior attempts at combating the transmission of sound and vibration to the environment in which the compressor is located have not been totally successful. U.S. Pat. No. 2,721,028 discloses an arrangement of resilient plastic blocks disposed upon the outer housing of the compressor to reduce the sound and vibration transmitted from the compressor housing. This design does not reduce vibration over a large area of the compressor housing.
Another U.S. Pat. No. 4,799,653, discloses a method of radial vibration attenuation in which concentric rings or tubes are separated radially by corrugated sheets or wires made of spring steel located in radially aligned grooves for attenuating radially occurring oscillations, damping shocks and vibration.
U.S. Pat. No. 2,205,138 discloses a cooling jacket for a motor compressor useful in compressing refrigerant. The cooling jacket comprises a coil of tubing wrapped about the compressor housing forming loops in thermal contact with a corrugated fin structure located within the compressor housing. As stated in the patent, slipping between the cooling coil loops, caused by transverse relative movement, would not be desirable or acceptable since it would reduce the cooling ability of the coils and increase the possibility of water leaks due to wear of the tubing walls. The water cooling jacket is not particularly useful as a sound deadening jacket as an additional sound jacket is needed about the compressor as shown in the patent. The additional sound reduction jacket is recommended to reduce sound induced by vibration of the casing which is triggered by impacts of the tubing walls between each other and with the external surface of the housing.
Many damping techniques are known, but the need for effective means for damping vibrations become more difficult to achieve as the external surface temperature of the compressor increases. Use of visoelastic polymer materials to reduce noise and vibration is common. However, it is difficult to obtain polymers capable of withstanding temperatures of above approximately 150.degree. C. for long periods of time and use of polymer material often affects heat transfer from the compressor to the environment.
It is therefore desired to overcome the aforementioned prior art problems associated with hermetic compressors to provide a simple sound damping system which is inexpensive and further increases heat transfer from the compressor.